Abstract

Interpopulational variation in reproductive costs may affect variation in life
history traits including reproductive investment (i.e. clutch mass relative to either
maternal body mass or length). While the relationships between reproductive investment
and costs of reproduction, especially costs to mobility, have been well studied in
squamate reptiles, how these costs relate to investment and explain patterns within
and between populations is not always straightforward. In the present study, we
examined the relationship between reproductive investment and costs of reproduction
(gravid and postpartum sprint speeds and maternal postpartum body condition)
in two populations of a viviparous skink, Pseudemoia entrecasteauxii living in different
habitat types. We found that costs of reproduction (i.e. impact on gravid and
postpartum sprint speeds) depended on the interaction between relative reproductive
burden (RRB) and population. There was no link between relative clutch mass (RCM)
and maternal sprint speeds. Maternal postpartum body condition was not related to
either RRB or RCM for either population. Gravid females living in the open habitat
population showed significantly slower sprint speed compared with the same females
immediately postparturition, and other gravid females living in a closed habitat population.
Such females are likely to experience a higher cost of reproduction in terms of
changes in sprint speed as well as exposure to predators and may show a behavioural
shift to crypsis in order to compensate for locomotor impairment and to reduce the
risk of predation. We suggest that factors which relate to costs of reproduction (i.e.
sprint speeds) are complex and may involve multiple factors such as reproductive
investment and habitat characteristics.